Compounds which inhibit the enzyme renin have been the subject of much research in recent years. Renin inhibitors are designed to mimic the peptide substrate of renin and, therefore, are peptide-like in their structure. However, in order to improve the biopharmaceutical properties of renin inhibitors, the compounds must be as non-peptide-like as possible. A renin inhibiting compound which has been found to be of particular interest is the compound of the formula: ##STR2## wherein R is a nitrogen-containing heterocycle which is bonded via a nitrogen atom to the sulfonyl group, R.sub.6 is hydrogen, alkoxy, halogen or loweralkyl, R.sub.7 is loweralkyl having 2 to 7 carbon atoms, and R.sub.8 is loweralkyl, cycloalkyl, or aryl or a pharmaceutically acceptable acid addition salt thereof. A heterocycle of particular interest is 1-methylpiperazin-4-yl.
A renin inhibiting compound of most interest is the compound of formula Ia: ##STR3## wherein R and R.sub.6 are defined as above or a pharmaceutically acceptable acid addition salt thereof.
Unlike a peptide, compound I is not composed of readily available amino acids. Therefore, methods are needed for the preparation of intermediates which are useful for the preparation of compounds such as I.